comparisons of gait variability and symmetry in healthy runners, runners with a history of lower limb injuries, and runners with a current lower limb injury

Background: running is a cyclic movement requiring bilateral symmetry between the lower limbs to reduce injury risk. the assessment of side-to-side differences is often performed to detect functional deficits. objectives: the purpose was to study side-to-side differences using clinical and running performance assessments in healthy runners (hr), runners with a history of lower limb injuries (rhi), and runners with a current lower limb injury (rli). methods: forty-three runners were recruited, with 14 participants being allocated to the hr group, 13 to the rhi group, and 16 to the rli group. peak vertical ground reaction force (grf), midfoot pressure, foot rotation, and gait variability were recorded using a zebris fdm-t treadmill analysis system. participants were also assessed using the navicular drop test. dependent t-tests were used to determine if any differences existed between the lower limbs within each group. one-way anovas were then used to investigate the side-to-side differences between the three groups. results: significant differences were seen in navicular drop height between lower limbs within both the hr (p = 0.02) and rhi (p = 0.009) groups, and side-to-side differences in foot rotation were greatest in the rli group (~ 34%) compared to both the rhi (~ 30.5%) and hr (~ 24%) groups. the lateral variability of the center of pressure was greatest in the rli group (37.1 mm) compared to the rhi (28.9 mm) and hr (22.2 mm) groups. conclusions: variability of butterfly center of pressure diagram may help identify runners at a greater risk of lower limb injury. side-to-side differences should be expected to progressively decrease from the injured stage, through the recovery and return to sport phases. target goals of less than 34% side-to-side difference for foot rotation and 37.1 mm for the lateral center of pressure variability may be used to help the decision-making process when considering a return to running practice.